Which behavioral disorder affects approximately 3-6% of students?

ADHD, or Attention Deficit Hyperactivity Disorder, is a behavioral disorder that affects a significant number of students, with estimates suggesting it impacts around 3-6% of the school-aged population. This condition is characterized by symptoms such as inattention, hyperactivity, and impulsivity, which can significantly impede a child's academic performance and social interactions.

The prevalence of ADHD highlights its recognition within educational settings, where educators and support staff are trained to implement specific interventions and support strategies to assist affected students. Given the commonality and noticeable impact of ADHD, it is often a focal point in special education discussions and planning.

In contrast, the other conditions listed do not exhibit the same prevalence rates in student populations. Mental retardation is an outdated term now more accurately referred to as intellectual disability, which affects a different segment of the population and not to the extent of ADHD. Epilepsy, though also significant, is primarily a neurological disorder rather than a behavioral one, while dysgraphia is specifically a learning disability affecting writing skills, with a prevalence that is less commonly reported compared to ADHD. Thus, ADHD's specific prevalence and its implications in educational settings substantiate its classification as the correct answer.